This application claims priority of Taiwanese application no. 092202516, filed on Feb. 18, 2003.
1. Field of the Invention
The invention relates to a scroll saw, more particularly to a scroll saw with a saw blade that is easy to replace.
2. Description of the Related Art
Referring to FIG. 1, a conventional scroll saw 1 is shown to include a pair of upper and lower driving arms 11, 12, a shank 13, a rotary knob 14, a biasing member 15, an upper blade holder 16, a lower blade holder 17, and a saw blade 18. The shank 13 is formed with a threaded section 131 that extends through a distal end 111 of the upper driving arm 11 so as to engage the rotary knob 14, and a coupling section 132 opposite to the threaded section 131 and coupled to the upper blade holder 16. The biasing member 15 is sleeved on the coupling section 132 and has one end abutting against the upper driving arm 11 and an opposite end abutting against the upper blade holder 16. The lower blade holder 17 is mounted fixedly on the lower driving arm 12. The saw blade 18 has an upper end portion 181 that engages removably the upper blade holder 16, and an opposite lower end portion 182 that engages removably the lower blade holder 17.
In use, when the rotary knob 14 is rotated to move the shank 13 upwardly, the upper blade holder 16 will move accordingly for increasing the tension of the saw blade 18 and for preventing removal of the saw blade 18 from the upper and lower blade holders 16, 17. On the other hand, when the rotary knob 14 is rotated to move the shank 13 downwardly, the saw blade 18 can be removed from the upper and lower blade holders 16, 17 for replacement purposes.
The following are some of the drawbacks of the aforesaid conventional scroll saw 1:
1. Quick attachment or removal of the saw blade 18 is not possible because of the need to rotate the rotary knob 14 before the upper blade holder 16 can be moved to engage or disengage from the upper end portion 181 of the saw blade 18.
2. Proper adjustment of the blade tension cannot be conveniently conducted due to the threaded engagement between the shank 13 and the rotary knob 14. When the tension of the saw blade 18 is too high, the saw blade 18 tends to break easily. On the other hand, when the tension of the saw blade 18 is too low, the saw blade 18 tends to wobble during a cutting operation.
Therefore, the object of the present invention is to provide a scroll saw that can overcome the aforesaid drawbacks associated with the prior art.
Accordingly, a scroll saw of this invention comprises:
upper and lower driving arms, each of which has a distal end;
a saw blade having upper and lower blade ends;
a blade retaining unit including a lower blade holder mounted on the distal end of the lower driving arm to hold removably the lower blade end, a pivot seat mounted pivotally on the distal end of the upper driving arm, and an upper blade holder mounted on the pivot seat, the pivot seat being pivotable relative to the upper driving arm from a first position, where the upper blade holder engages the upper blade end, to a second position, where the upper blade holder disengages from the upper blade end;
a push rod having a connecting end coupled to the pivot seat, and a pressing end opposite to the connecting end;
a biasing unit for providing a biasing force that enables the pivot seat to pivot to the first position; and
an actuating unit operable so as to provide a pressing force on the pressing end of the push rod for enabling the push rod to push the pivot seat to pivot to the second position against biasing action of the biasing unit so as to permit release of the saw blade from the upper and lower blade holders.